A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
This application includes a computer program listing appendix on a single compact disc, the contents of which are herein incorporated by reference. The compact disc contains four files; a 5.73 kb file entitled 09-526710-1, a 9.05 kb file entitled 09-526710-2, a 22.8 kb file entitled 09-526710-3, and a 3.47 kb file entitled 09-526710-4, each created on Aug. 6, 2002.
The invention pertains to the field of input devices for handheld computers in general, and to PCMCIA defined PC card interfaces between barcode scanning devices and other input devices and portable computers in particular.
Portable barcode scanning systems are useful for many applications such as inventory control. Portable barcode scanning systems exist in the prior art and are commercially available from such vendors as Symbol Technologies, Inc. of Bohemia, N.Y. and Telxon. To date however portable barcode scanners have been custom units of proprietary design. An example of a custom designed, proprietary portable barcode scanning system is the model PTC-600 available from Telxon. This device uses a custom designed portable computer to which is attached a clip-on barcode scanning engine. This technology is described in more detail in U.S. Pat. No. 4,621,189, the teachings of which are incorporated by reference. However the process of decoding barcodes is well known and can be done by any suitably programmed computer having appropriate interface circuitry so there is no need to buy a custom designed computer system simply to do one type of task when a general purpose computer with suitable peripheral circuitry and software can do the same task as well as other tasks. Further, there is a disadvantage to the consumer in that as better barcode scanning engines or better computers become available, the consumer is precluded from using them in a custom designed system unless he or she is willing to give up their investment in the custom designed system already purchased.
With the introduction of palmtop computers, Personal Communicators such as the ATandT EO and Personal Digital Assistants (hereafter PDA""s) there has arisen a need to modify these general purpose devices for use with various input devices such as barcode scanning engines to create xe2x80x9copen systemxe2x80x9d non-proprietary portable barcode scanning apparatus.
Therefore, there is described herein an open system interface for various input devices such as bar code scanners, magnetic stripe readers etc. which can be integrated onto a PCMCIA defined PC card.
The teachings of the invention contemplate a genus of interfaces for portable laserscanning, charge coupled device and wand type barcode scanning engines, magnetic stripe and magnetic ink readers, keyboards or 10-key keypads, optical character recognition devices, and trackballs using PCMCIA defined PC cards to interface these devices with host PDA""s or palmtop computers.
The advantages of implementing interfaces for frequently used input devices on industry standard PC cards are plentiful. First and foremost is the fact that such an xe2x80x9copen systemxe2x80x9d combination gives the user the advantage of not being locked into a proprietary technology that can become obsolete in a matter of months in the fast moving world of high tech electronics. What this means to a user is that when a better PDA or palmtop computer comes out, the user does not have to buy all new input devices designed specifically to work only with that computer as long as the new computer has an industry standard PC card slot. Thus, if the manufacturer of the new computer does not offer a proprietary CCD or laser based barcode scanner, the user is not precluded from using such an input device as long as the new computer has a PC card slot. Likewise, when a new input device with better features appears on the market, the user is not precluded from switching to the new input device for use with his or her existing PDA so long as he or she has a PC card implementing an appropriate interface for the new input device to convert the output of the new input device to signals on 68 pin bus defined by PCMCIA standards accepted industry wide.
In one embodiment of the interface for a laser type barcode scanning engine, the PCMCIA defined PC card has attached thereto a housing which contains a visible light laser diode, scanning optics and a photodetector. The scanning optics scan a laser beam across a barcode and detect reflected light. In some embodiments, the PCMCIA defined PC card has circuitry integrated thereon to sample the analog signal from the photodetector and create a digital image thereof in memory and decode the digital image in memory into an ASCII or EBCDIC character string representing the alphanumeric text encoded into the barcode (ASCII or EBCDIC are industry standard codes that define for each alphanumeric character a unique string of 1""s and 0""s that are a binary code for that character). In addition there is circuitry integrated on the PCMCIA defined PC card to send the decoded data from the photodetector to the host PDA for use by an application program in execution thereon.
In some embodiments, the PC card interface contains circuitry to sample TTL level or wand type signals from an input device and send the sample data to a host computer through the PCMCIA slot. The host computer then decodes alphanumeric characters from the sample data.
In other embodiments, the PC card interface contains circuitry to make the TTL level or wand type signal available on a pin of the PCMCIA bus where the host periodically samples the voltage level on the pin and creates a sample buffer. The alphanumeric characters encoded in the samples are then decoded by the host computer.
In one embodiment, the signal from an undecoded barcode scan engine or other input device that outputs electrical signals that encode alphanumeric characters is coupled to a specially programmed decoder chip on the PC card. The barcode scan engine or other input device is either external to the PC card or physically mounted thereon. The decoder chip decodes the electrical signals into alphanumeric characters and generates an interrupt to the host computer through a pin on the PCMCIA bus. The host computer then does an I/O transaction to the PC card to retrieve the decoded data. In one particularly useful species of this genus, the PC card includes nonvolatile memory which may be accessed by the host computer through the PCMCIA bus without blocking access to the decoder through the PCMCIA bus. In this way, host computers that are memory limited like PDA""s may replace their PC memory card with a barcode decoder PC card having on-board nonvolatile memory and have the benefit of both PC card barcode decoding (or access to data from other types of input devices) while not losing the benefit of also have external nonvolatile memory which may be used for any purpose.